HUMERAL SHAFT FRACTURES
Non-Operative Success Rate High | Radial Nerve at Risk | Functional Bracing Gold Standard
AO/OTA CLASSIFICATION (12-A/B/C)
Critical Must-Knows
- Functional bracing achieves over 90% union with acceptable alignment in most cases
- Radial nerve spirals around posterior humerus - vulnerable at junction of middle and distal thirds
- Holstein-Lewis fracture: Distal third spiral fracture with high radial nerve palsy risk
- Acceptable alignment: under 20° anterior angulation, under 30° varus/valgus, less than 3cm shortening, under 15° rotation
- Primary radial nerve palsy (at injury): observe 3-4 months before exploration
Examiner's Pearls
- "70% of radial nerve palsies recover spontaneously without exploration
- "Secondary palsy after manipulation = urgent exploration
- "Pendulum exercises begin immediately with functional brace
- "Antegrade IMN avoids radial nerve but risks rotator cuff injury
Clinical Imaging
Imaging Gallery
Critical Humeral Shaft Fracture Exam Points
Radial Nerve Assessment
Document wrist/finger extension and sensation before any manipulation. Primary palsy = observe, Secondary palsy post-manipulation = explore. Nerve crosses posterior humerus at spiral groove.
Functional Bracing
Gold standard non-operative management. Humeral brace with adjustable straps. Allows elbow and shoulder motion. Gravity alignment maintains reduction.
Surgical Indications
Polytrauma, open fractures, vascular injury, floating elbow, bilateral fractures, pathological fractures. Also consider for unacceptable alignment and patient factors (obesity).
Operative Options
ORIF with plate vs IMN. Plates preferred for distal fractures (avoid rotator cuff). IMN for proximal/middle shaft. MIPO technique reduces iatrogenic nerve injury.
At a Glance Treatment Decision Guide
Quick Decision Guide
| Fracture Pattern | Nerve Status | Key Factor | Treatment |
|---|---|---|---|
| Simple, acceptable alignment | Intact | Compliant patient | Functional brace - gold standard |
| Simple fracture | Primary radial palsy | Closed injury | Functional brace + observe nerve 3-4 months |
| Any pattern | Secondary palsy post-manipulation | New deficit after reduction | Urgent ORIF + nerve exploration |
| Holstein-Lewis (distal spiral) | With or without palsy | High nerve risk location | Strong consideration for ORIF |
| Open/Polytrauma/Floating elbow | Any status | Associated injuries | ORIF or IMN mandatory |
Key Mnemonics
WESTRadial Nerve Motor Testing
Memory Hook:WEST - Wrist drop is the classic finding! Test wrist extension against gravity, if absent = radial nerve palsy.
STOP BRACESurgical Indications for Humeral Shaft
Memory Hook:STOP the BRACE when surgery is needed - these are your absolute and relative surgical indications!
20-30-3-15Acceptable Angulation (Rule of 20-30-3-15)
Memory Hook:20-30-3-15: The shoulder hides angulation well, making humeral shaft fractures forgiving for non-operative management!
HoLLyHolstein-Lewis Fracture Features
Memory Hook:HoLLy Hurts the Radial nerve! Distal third spiral = high risk for nerve injury = consider ORIF.
Overview and Epidemiology
Clinical Significance
Humeral shaft fractures are unique in that non-operative management achieves excellent outcomes in the majority of cases. The shoulder and elbow joints compensate well for residual angulation and shortening, making functional bracing the gold standard treatment.
Demographics
- Bimodal distribution: Young males (high-energy), elderly females (low-energy falls)
- Male predominance in working age (sports, MVA)
- Female predominance in elderly (osteoporotic)
- Mean age: 45-55 years
Mechanism
- Direct blow: Transverse fractures (50%)
- Indirect/Torsion: Spiral/oblique fractures (50%)
- Falls (most common overall)
- Motor vehicle accidents
- Sports (throwing, arm wrestling)
Fracture Distribution by Location
| Location | Frequency | Common Pattern | Nerve at Risk |
|---|---|---|---|
| Proximal third | 30% | Spiral/Oblique | Axillary nerve (rare) |
| Middle third | 60% | Transverse/Spiral | Radial nerve (spiral groove) |
| Distal third | 10% | Spiral (Holstein-Lewis) | Radial nerve (highest risk) |
Anatomy and Pathophysiology
The Radial Nerve Course
The radial nerve is the most commonly injured nerve in humeral shaft fractures. It enters the posterior compartment from medial to lateral, wrapping around the posterior humerus in the spiral groove at the junction of the middle and distal thirds. Here it is tethered by the lateral intermuscular septum.
Muscular Deforming Forces by Fracture Level
| Fracture Level | Proximal Fragment | Distal Fragment | Resulting Deformity |
|---|---|---|---|
| Above pectoralis major insertion | Abduction, ER (rotator cuff) | Adduction (pec major, deltoid) | Apex lateral angulation |
| Between pec major and deltoid | Adduction (pec major) | Abduction (deltoid) | Apex medial angulation |
| Below deltoid insertion | Abduction (deltoid) | Proximal pull (biceps, triceps) | Shortening, variable angulation |
Key Anatomical Landmarks
- Surgical neck: Transition to shaft (axillary nerve)
- Deltoid insertion: V-shaped, mid-shaft lateral
- Spiral groove: Posterior, middle-distal junction
- Supracondylar ridge: Transition to distal humerus
Radial Nerve Anatomy
- Enters arm in axilla (posterior cord)
- Supplies triceps proximally
- Spiral groove: 14-20cm from lateral epicondyle
- Pierces lateral intermuscular septum at distal third
- Divides into PIN and superficial radial at elbow
Exam Trap: Radial Nerve Branches
The radial nerve supplies the triceps before entering the spiral groove. Therefore, triceps function may be preserved despite radial nerve injury at the spiral groove level. Always test wrist and finger extension - these are the key clinical findings for radial nerve palsy.
Classification Systems
AO/OTA Classification (12-A/B/C)
| Type | Description | Subgroups | Treatment Tendency |
|---|---|---|---|
| 12-A (Simple) | Two fragments, over 90% cortical contact | A1: Spiral, A2: Oblique (over 30°), A3: Transverse (under 30°) | Functional bracing |
| 12-B (Wedge) | Three fragments, contact between main fragments possible | B1: Spiral wedge, B2: Bending wedge, B3: Fragmentary wedge | Bracing or surgery |
| 12-C (Complex) | Multiple fragments, no contact between main fragments | C1: Spiral, C2: Segmental, C3: Irregular comminuted | Usually surgical |
Key Point
AO/OTA classification determines complexity and comminution. Simple fractures (A) have excellent outcomes with functional bracing. Complex fractures (C) often require surgical stabilization.
Clinical Assessment
History
- Mechanism: Direct blow vs torsion vs fall
- Hand dominance: Functional implications
- Occupation: Manual vs sedentary work
- Comorbidities: Diabetes, smoking, osteoporosis
- Previous injury: Pathological fracture concern
Examination
- Look: Deformity, swelling, bruising, skin condition
- Feel: Point tenderness, crepitus, neurovascular status
- Move: Limited by pain, test shoulder and elbow
- Neurovascular: Radial nerve critical, brachial artery
Radial Nerve Examination is MANDATORY
Document radial nerve function before and after any intervention. Test: wrist extension against gravity, finger MCP extension, thumb extension (hitchhiker), sensation first dorsal web space. Record in notes clearly.
Radial Nerve Assessment
| Test | Technique | Finding | Interpretation |
|---|---|---|---|
| Wrist extension | Extend wrist against resistance | Wrist drop if absent | Radial nerve palsy - most reliable sign |
| Finger MCP extension | Extend fingers at MCP against resistance | Cannot extend MCPs | PIN involvement |
| Thumb extension | Extend thumb (hitchhiker sign) | Cannot extend thumb | EPL - PIN involvement |
| Sensation first web space | Light touch dorsal first web | Numbness/decreased | Superficial radial nerve |
| Triceps function | Extend elbow against resistance | Usually preserved | Branches given before spiral groove |
Primary vs Secondary Palsy
Primary palsy (present at injury): Usually neurapraxia from stretch/contusion. Observe for 3-4 months - 70% recover spontaneously. Secondary palsy (develops after manipulation/reduction): Suggests nerve entrapment in fracture site - warrants urgent exploration.
Investigations
Imaging Protocol
AP and lateral of entire humerus. Must include shoulder and elbow joints. Assess fracture pattern, displacement, angulation, and any articular involvement.
Include shoulder and elbow joints on separate views if not fully visualized. Rule out associated injuries (floating elbow, shoulder dislocation).
Indicated for: articular extension, preoperative planning for comminuted fractures, pathological fracture workup.
MRI: pathological fracture evaluation, soft tissue injury. Angiography: if vascular injury suspected (rare).
Radiographic Assessment
| Parameter | What to Assess | Normal/Acceptable | Action if Abnormal |
|---|---|---|---|
| Fracture pattern | Simple vs comminuted | Simple preferred for bracing | Comminuted may need surgery |
| Sagittal angulation | AP view | less than 20 degrees | Reduction needed if over 20° |
| Coronal angulation | Lateral view | less than 30 degrees | Reduction needed if over 30° |
| Shortening | Compare with normal | less than 3cm | Usually acceptable |
| Joint involvement | Shoulder and elbow | None | CT if suspected |
Holstein-Lewis Recognition
Look specifically for distal third spiral oblique fracture pattern on radiographs. This is the Holstein-Lewis fracture with high radial nerve palsy risk. Even with intact nerve function, consider lower threshold for surgical intervention.
Management Algorithm
Non-Operative Management - Functional Bracing
Gold standard for most humeral shaft fractures. Pioneered by Sarmiento, achieves over 90% union rate.
Functional Bracing Protocol
Coaptation splint (sugar tong) or U-slab. Sling for comfort. Ice, elevation. Begin pendulum exercises immediately if pain allows.
Convert to prefabricated humeral brace once swelling subsides. Circumferential compression with adjustable straps. Allows elbow and shoulder motion.
Active shoulder and elbow ROM. Pendulum exercises 4-6 times daily. Gravity alignment maintains reduction. Wean sling.
Weekly X-rays initially to ensure maintained alignment. Then every 2-4 weeks until union (usually 8-12 weeks).
Wean brace once clinical and radiographic union. Progressive strengthening. Full activity by 4-6 months.
Functional Bracing Mechanism
The brace provides hydraulic compression via soft tissue containment. This, combined with gravity, aligns the fracture. The key is early motion - muscle contraction maintains alignment and promotes healing.
Success Factors
- Compliant patient
- Simple fracture pattern
- Acceptable initial alignment
- Early active motion
- Weekly X-ray follow-up initially
Poor Brace Candidates
- Obesity (poor soft tissue compression)
- Skin problems (burns, dermatitis)
- Non-compliance
- Transverse fractures at narrow isthmus
- Segmental fractures
Surgical Technique
Open Reduction Internal Fixation - Plating
Patient Positioning:
- Supine with arm on arm board (anterolateral approach)
- Lateral decubitus or prone for posterior approach
- Beach chair for proximal fractures
Anterolateral Approach:
- Incision along lateral border of biceps
- Develop interval between brachialis (musculocutaneous) and brachioradialis (radial)
- Radial nerve runs between these muscles - identify and protect
- Plate applied anterolaterally on flat humerus
Posterior Approach:
- Midline posterior incision
- Split triceps in midline or elevate medial and lateral heads
- Radial nerve identified in spiral groove, protected
- Plate applied to flat posterior surface
Plate Choice:
- 4.5mm narrow LCP or broad LCP
- Minimum 3-4 screws (6-8 cortices) each side of fracture
- Compression plate for simple patterns
- Bridge plating for comminution
MIPO Technique
Minimally Invasive Plate Osteosynthesis uses small incisions proximally and distally with submuscular plate passage. Reduces soft tissue stripping and theoretical nerve injury risk. Requires fluoroscopy.
Complications
Complications and Management
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Radial nerve palsy | 12-18% (primary) | Distal third, spiral, Holstein-Lewis | Observe primary, explore secondary |
| Nonunion | 2-10% | Transverse pattern, distraction, non-compliance | ORIF + bone graft |
| Malunion | Variable | Non-operative with poor follow-up | Usually well tolerated, osteotomy if symptomatic |
| Shoulder stiffness | Common initially | Prolonged immobilization, poor compliance | Early motion, physiotherapy |
| Infection (surgical) | 1-3% | Open fractures, poor soft tissues | Debridement, antibiotics, revision |
| Hardware failure | 2-5% | Early loading, inadequate fixation | Revision fixation |
| Iatrogenic nerve injury | 2-5% (surgical) | Posterior approach, ORIF | Careful dissection, MIPO technique |
Radial Nerve Palsy Management
Management Algorithm
Primary palsy (at injury): 70% recover spontaneously. Observe for 3-4 months with clinical and EMG monitoring. If no recovery by 4 months, explore. Secondary palsy (post-manipulation): Urgent exploration - nerve likely trapped in fracture site.
Primary vs Secondary Radial Nerve Palsy
| Feature | Primary Palsy | Secondary Palsy |
|---|---|---|
| Timing | Present at injury | Develops after manipulation/surgery |
| Mechanism | Stretch/contusion (neurapraxia) | Entrapment in fracture site |
| Spontaneous recovery | 70% within 3-4 months | Unlikely without exploration |
| Management | Observe, wrist splint, EMG at 3-4 weeks | Urgent surgical exploration |
Management of Primary Radial Nerve Palsy
Document findings clearly. Wrist cock-up splint to maintain function. Proceed with non-operative management if otherwise indicated.
Baseline EMG/NCS to confirm nerve injury type and level. Monitor clinically for Tinel sign progression (sign of regeneration).
Repeat EMG if no clinical recovery. Look for reinnervation potentials. Continue monitoring.
If no clinical or EMG recovery, plan surgical exploration. Nerve grafting may be required if gap identified.
If nerve recovery incomplete, consider tendon transfers (PT to ECRB, FCR to EDC, PL to EPL).
Tendon Transfer Options
If radial nerve does not recover: PT to ECRB (wrist extension), FCR to EDC (finger extension), PL to EPL (thumb extension). These restore functional wrist and finger extension.
Nonunion Risk Factors
Transverse fracture pattern has higher nonunion risk with functional bracing (2-10% vs 5% or less for oblique/spiral). The narrow isthmus and transverse orientation provide poor cortical contact. Consider primary ORIF for transverse fractures at the narrow diaphyseal portion.
Shoulder Stiffness Prevention
Pendulum exercises from day one are critical. The key to successful functional bracing is EARLY MOTION. Shoulder stiffness is a preventable complication with appropriate rehabilitation.
Postoperative Care and Rehabilitation
Post-ORIF Rehabilitation
Sling for comfort. Wound care. Gentle pendulum exercises. No active shoulder elevation against gravity.
Active-assisted shoulder ROM. Active elbow ROM. Gentle strengthening begins at 4 weeks if stable fixation.
Progressive resistive exercises. Wean sling. Radiographic union usually evident by 8-12 weeks.
Full activity when clinically and radiographically healed. Sport-specific training as appropriate.
Outcomes and Prognosis
Prognostic Factors
| Factor | Impact | Notes |
|---|---|---|
| Fracture pattern | Significant | Simple patterns do well with bracing; transverse at risk |
| Patient compliance | Critical for bracing | Non-compliance leads to malunion/nonunion |
| Radial nerve status | Important | Primary palsy usually recovers; secondary needs surgery |
| Associated injuries | Variable | Polytrauma patients may need surgical fixation |
| Smoking | Negative | Higher nonunion rates |
| Diabetes | Negative | Delayed healing, higher complications |
Plate vs Nail Outcomes
Meta-analyses show similar union rates for plate vs nail (both over 95%). However, plating has lower reoperation rates and less shoulder problems. Nailing is faster but associated with more shoulder pain (antegrade) or elbow issues (retrograde).
Evidence Base
Sarmiento Functional Bracing Study
- 922 humeral shaft fractures treated with functional bracing
- 98% union rate achieved
- Mean time to union 10 weeks
- Acceptable outcomes with up to 20° sagittal and 30° coronal angulation
Plate vs Nail Meta-Analysis
- Meta-analysis of 6 RCTs comparing plate and nail fixation
- Similar union rates for plate (94%) vs nail (92%)
- Plating had lower reoperation rate (7% vs 22%)
- Fewer shoulder problems with plating
Radial Nerve Palsy Natural History
- Meta-analysis of 4517 fractures
- Primary radial nerve palsy in 11.8%
- Spontaneous recovery in 70.7%
- No significant difference between exploration and observation for closed fractures
Holstein-Lewis Fracture Nerve Injury
- Original description of distal third spiral oblique fracture
- High radial nerve palsy rate (22-32%)
- Nerve trapped between proximal spike and lateral intermuscular septum
ORIF vs Functional Bracing RCT
- RCT of 110 patients
- ORIF showed faster union (3 vs 5 months) and earlier return to work
- No difference in final outcomes
- Higher cost with surgery
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Initial Assessment and Classification
"A 35-year-old man presents after falling off a ladder onto his outstretched arm. He has obvious deformity of his right upper arm and cannot extend his wrist or fingers. X-rays show a spiral fracture of the distal third of the humerus. How would you assess and manage this patient?"
Scenario 2: Surgical Decision-Making
"A 55-year-old woman sustains a closed transverse humeral shaft fracture at the mid-diaphysis in a motorcycle accident. She also has a closed tibial shaft fracture. Her radial nerve is intact. How would you manage this patient?"
Scenario 3: Complication Management
"You are called to see a 40-year-old man in ED who had a closed humeral shaft fracture reduced in a backslab by the junior doctor. He now cannot extend his wrist or fingers - he had normal function before the reduction. What is your management?"
MCQ Practice Points
Anatomy Question
Q: At what level does the radial nerve cross the posterior humerus in the spiral groove? A: The junction of the middle and distal thirds, approximately 14-20cm from the lateral epicondyle. Here it is tethered by the lateral intermuscular septum.
Classification Question
Q: What is a Holstein-Lewis fracture? A: A distal third spiral oblique fracture of the humerus with high radial nerve palsy rate (22-32%). The sharp proximal spike can trap or lacerate the radial nerve at the lateral intermuscular septum.
Management Question
Q: What are the acceptable angulation limits for humeral shaft fractures treated non-operatively? A: Less than 20° sagittal (AP) angulation, less than 30° coronal (varus/valgus), less than 3cm shortening, less than 15° rotation. The shoulder compensates well for these deformities.
Nerve Question
Q: A patient develops wrist drop after manipulation of a humeral shaft fracture. What is your management? A: This is secondary radial nerve palsy - the nerve is likely trapped in the fracture. Urgent exploration is required. Do not observe as you would for primary palsy.
Treatment Question
Q: What is the expected spontaneous recovery rate for primary radial nerve palsy in closed humeral shaft fractures? A: 70% recover spontaneously within 3-4 months. Observe with wrist splint and EMG monitoring. Explore if no recovery by 4 months.
Australian Context and Medicolegal Considerations
Australian Data
- Common ED presentation (21/100,000)
- Bimodal: young males, elderly females
- Functional bracing mainstay of treatment
- Plating preferred over nailing when surgery indicated
RACS/AOA Guidelines
- Competency expected in non-operative and operative management
- Clear documentation of radial nerve status mandatory
- Informed consent must include nerve injury discussion
- Orthopaedic exam commonly tests radial nerve assessment and management
Medicolegal Considerations
Key documentation requirements:
- Document radial nerve function before AND after any manipulation
- Record complete motor (wrist, finger, thumb extension) and sensory (dorsal first web) exam
- Document discussion of treatment options including functional bracing vs surgery
- Informed consent for surgery must include: infection, nonunion, nerve injury (especially iatrogenic), shoulder stiffness (IMN), need for hardware removal
- If radial palsy present: document as primary vs secondary and management plan
Consent for Humeral Shaft ORIF
Specific risks to discuss: Radial nerve injury (iatrogenic 2-5%), infection, nonunion, hardware failure/irritation, need for bone grafting, shoulder stiffness. For IMN: add rotator cuff injury and shoulder pain (15-30%).
HUMERAL SHAFT FRACTURES
High-Yield Exam Summary
Key Anatomy
- •Radial nerve in spiral groove at middle-distal third junction
- •Nerve tethered by lateral intermuscular septum
- •Triceps branches given BEFORE spiral groove (usually spared)
- •Muscular deforming forces vary by fracture level
Classification
- •AO/OTA: 12-A (simple), B (wedge), C (complex)
- •Holstein-Lewis: distal third spiral = high radial palsy risk
- •Location: proximal (30%), middle (60%), distal (10%)
- •Pattern: transverse (direct blow), spiral (torsion)
Acceptable Alignment (20-30-3-15)
- •under 20° sagittal (AP) angulation
- •under 30° coronal (varus/valgus) angulation
- •less than 3cm shortening
- •under 15° rotation
Treatment Algorithm
- •Most fractures: Functional bracing (over 90% union)
- •STOP BRACE indications: Segmental, Transverse isthmus, Open, Polytrauma, Bilateral, Radial 2° palsy, Arterial injury, Cannot tolerate, Extended joints (floating elbow)
- •Plate preferred over nail (less shoulder pain, lower reop rate)
- •MIPO technique reduces iatrogenic nerve injury
Radial Nerve Palsy
- •Primary palsy: observe 3-4 months, 70% recover
- •Secondary palsy (post-manipulation): URGENT exploration
- •Test: wrist extension, finger MCP extension, thumb extension
- •Tendon transfers if no recovery: PT-ECRB, FCR-EDC, PL-EPL